Terrestrial broadcast services for small mobile devices with small antennas, e.g. for mobile TV in mobile phones, belong to an area that has gained a lot of attention. Multimedia service transmission intended for multiple receivers, e.g., Multimedia Broadcast and Multicast Services (MBMS), has been defined and developed for GSM and WCDMA mobile systems. Also for CDMA2000 there is a similar concept. In addition, standalone broadcast systems has been developed, e.g. DVB-H. All of these technologies, and related technologies, for terrestrial broadcast services for small handheld mobile devices, are subsequently referred to as MBMS or multimedia services.
It is possible to implement an MBMS system that is optimized for broadcast services, that only uses a Downlink (DL), i.e. non-duplex communication where information flows over the wireless interface only in the direction from Base Station (BS) to a receiver, such as a UE. A particular benefit of a downlink only system is that no radio spectrum resources are needed for an uplink (UL). Radio carrier and spectrum resources are needed only for the DL. Another benefit is that the radio characteristics of an UL can be ignored, and thus, efficiency-optimized DL-only Base Stations with high output power, and good coverage can be developed for such systems. Such MBMS systems, that only uses a wireless DL, is subsequently referred to as MBMS dedicated carrier (DC) systems or shortly Dedicated Carrier (DC) systems.
Terrestrial wireless systems that have MBMS functionality or techniques, and also can handle UL transmissions on radio spectrum resources that are either the same as the DL, or paired with spectrum resources of the DL, are referred to as MBMS mixed carrier (MC) systems, or shortly mixed carrier (MC) systems. The UL in a MBMS MC system could be used for UL signalling and/or for non-MBMS services requiring an UL, e.g. unicast services, as described below.
Terrestrial wireless systems that have the capability of point-to-point communication between the BS and the UE, UL or DL or both, are subsequently referred to as Unicast capable system, or shortly Unicast (UC) systems. Typical UC user services include voice-calls, video-calls, internet web-browsing, sending a message, etc.
A common deployment scenario for MBMS DC systems is that such a system is overlaid on a UC network, meaning that the DC and UC systems overlap in geographical coverage. The overlaid DC and UC systems may use the same or different network equipment and network resources or a combination. For example, such scenarios have been foreseen in discussions in 3GPP, where an MBMS DC system typically would be overlaid on a UC GSM, WCDMA, Long Term Evolution (LTE) network, and a typical UE would be capable of MBMS services distributed by MC or DC, and UC services.
As will be explained below, broadcasting or multicasting in systems such as MBMS systems or the like are also denoted multimedia service transmission intended for multiple receivers. The communication resource, not being a part of the MBMS system or the like, used for transferring feedback information from the UEs over the UC system is later also denoted as a different communication means. This different communication means can be of limited resources. In this document, the term limited resources, such as limited network resources, communication resources or transmission resources, means that these resources are momentarily limited. That is, these resources are at any given moment in time finite.
Network operators typically initiate network tuning based on results of statistics data collection and post-processing. This is how the network is optimized, e.g. protocol parameters are optimized to give best experienced user performance, radio and antenna parameters are optimized for good coverage, etc. Network tuning for optimization is a continuous process in the operation of a network.
Also responses regarding other information than network specific measurements can be ordered by the network. Such responses can include interactive services, such as voting or any other interactive operation that requires feedback from the UEs to an entity in the network, such as a management entity or the like.
Broadcast mechanisms have been proposed for initiating and controlling UE statistics measurements for MBMS. Also responses regarding other information than network specific measurements can be ordered by the network. Such responses can include interactive services, such as voting or any other interactive operation that requires feedback from the UEs.
When using broadcast mechanisms for controlling measurements or ordering interactive services, the MBMS network does not know how many UEs that are receiving this broadcast or even how many UEs that are in an active mode in the system. It is therefore impossible for the MBMS network to know how many UEs that will be triggered to perform such measurements or other reporting and how many UEs that will attempt to report the results of such measurements.
The primary bottleneck for these report peaks is the wireless interface of the communication means carrying the responses. It is assumed that other network nodes can store and forward such measurement reports and thereby better handle such overload peak situations. If not properly designed, the reporting of such measurements could result in peaks of high overload in the wireless interface of the communication means carrying the responses. The risk of getting peaks of overload is especially high in broadcast or multicast systems, since a request to report measurements can be received by a large number of UEs more or less simultaneously and there is a great possibility that this large number of UEs also respond to these requests more or less simultaneously.